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Structural steel can be rolled into various shapes and sizes in rolling mills. Usually sections
having larger moduli of section in proportion to their cross-sectional areas are preferred. Steel
sections are usually designated by their cross-sectional shapes. The shapes of the rolled steel
sections available today have been developed to meet structural needs. Cross-section and size
are governed by a number of factors: arrangement of material for optimum structural efficiency;
functional requirements (surfaces that are easy to connect to, flat surfaces suitable for supporting
other materials, etc.,) dimensional and weight capacity of rolling mills, and material properties
which, for example, inhibit the hot rolling of wide thin elements because of excessive warping
or cracking that might occur.
I.S Hand Book No. 1 published by the Bureau of Indian Standards provides the dimensions,
weights and geometrical properties of various sections. Structural shapes are abbreviated by a
certain system described in the hand book for use in drawings, specifications and designs.
The types of rolled structural steel sections are as follows:
- Rolled steel I-sections Fig. 13.5(a)
- Rolled steel channel sections Fig. 13.5 (b)
- Rolled steel T-sections Fig. 13.5 (c)
- Rolled steel angle-sections Fig. 13.5 (d)
- Rolled steel tube-sections Fig 13.5 (e)
- Rolled steel bars Fig. 13.5 (f)
- Rolled steel flats Fig. 13.5 (g)
- Rolled steel plates
- Rolled steel sheets
- Rolled steel strip
p2IQS #2 2 Angle sections were probably the first shapes rolled and produced in 1819 in America.
I-beam shape was introduced by Zores of France in 1849. By 1870 Channels and Tees were
developed. All these early shapes were made of wrought iron. The first true skeletal frame
structure, the Home Insurance Company Building, was built in Chicago in 1884.
An I-section is designated by its depth and weight, e.g., I.S.L.B. 500 @ 735.7 N/m means, the
I-section is 500 mm deep and the self weight is 735.7 N per metre length.